JPS58130780A - Pulse drive device for dc motor - Google Patents

Abstract

PURPOSE:To reduce the variation in the rotary angle due to the variation in a load by applying a sufficiently high voltage to a DC motor during the starting period of the motor and shortcircuiting the terminals of the motor at the stopping time. CONSTITUTION:In case that a pulse becoming low level during the time t1(t1<tw) from other input terminal 29 when a drive pulse becoming high level during the time tw is inputted from an input terminal 28, a transistor 31 turns ON, while a transistor 32 turns OFF, and a power source voltage is applied directly to a DC motor 13. When the time t1 is elapsed, the transistor 31 turns OFF, and a DC motor 13 is driven by an electronic governor circuit 26. When the time tw is elapsed, the transistors 30, 32 turn ON, the operation of the governor circuit 26 is stopped, and the terminals of the motor 1 are shortcircuited, thereby causing the motor to instantaneously stop.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse drive device for a DC motor, and particularly to a pickup arm drive mechanism of a device (video disk playback device) that plays back signals from a disc-shaped recording medium such as a video disk. The pulse drive system of the DC motor used *K[mjru.

Hereinafter, the present invention will be explained using a pickup arm drive mechanism of a video disc recording device as an example, but the present invention is not limited to this, but can be used for general DC motors that perform pulse drive.

Currently, from video discs on which video signals etc. are recorded,
The following three methods have been proposed for the so-called video disk caterpillar device that reproduces Eirin signals and the like.

(17 A guide groove is provided on the video disc to read the change in capacitance (, 'HD method.

(2) A VHD method that reads capacitance changes without providing guide grooves on the video disc.

(3) A method that uses a laser or the like to optically cut off the signal.

In any of the above-mentioned methods, the image reproduction mode includes not only normal reproduction, but also static m + M raw, slow motion scene horse owner, ^ speed raw, and even quick reproduction by detecting the first stage of the moon at high speed. There are various modes of random access playback.

Therefore, in any playback method, the arm equipped with the pickup head is moved in a predetermined direction (forward or reverse).
K. It is necessary to move according to each playback mode.

Also, depending on the recording/playback method, at the start of playback, a pickup arm placed at a position away from the video disc is moved from that position at high speed to a position where playback is possible.
A so-called lead-in operation is required. In this case,
The arm feed speed is approximately 1000 times faster than during normal playback.
It reaches twice as much.

Below, using one DC motor, as mentioned above,
A conventional pickup arm drive mechanism that moves the pickup arm from low speed to high speed will be explained using the negative side.

FIG. 1 is a block diagram showing an example of the basic configuration of a conventional pickup arm drive mechanism. In the following explanation, for convenience of explanation, the drive mechanism shown in FIG. Even when used in an optical video disc playback device,
Its basic configuration is S-like.

In FIG. 1, reference numeral 1 denotes a video disc on which signals are recorded, and is made of, for example, polyvinyl chloride containing a conductive material. Further, this video disc 1 has a recording trunk formed of a string of minute bits. That is, an appropriate carrier wave is used as an information signal, and the information signal is recorded as a bit string corresponding to the modulated carrier wave.

2 is a needle that constitutes the head for taking the recorded (l! number 1), and a needle tip 2α is arranged at its tip. This needle tip 2a has a - sufficiently larger than the trunk width. The needle tip 2α is made of sapphire or the like, and an electrode with a width approximately equal to the width of the recording trunk is provided.The signal recorded on the video disc 1 is transmitted between the electrode of the needle tip 2α and the video disc 1. It is cut off as a change in capacitance between

An example of such a variable capacity video disc without a guide groove is shown in Nikkei Electronics J1978.10-50, pages 42-47, published by Nikkei McGraw-Hill.

The capacitance value change detected at the needle tip 2α is read as an information signal by a signal detection circuit 5, and is further supplied to a signal processing circuit 4 that performs demodulation and the like. This signal processing circuit 4
The output is supplied to a video monitor (not shown) and reproduced as a video.

On the other hand, the output of the signal detection circuit 6 is supplied to the needle control circuit 5. The needle control circuit 5 extracts tracking information from the input information signal. This tracking information is obtained by superimposing and recording a tracking control signal on a video disc in advance using a signal having a frequency different from that of a carrier wave of an information signal such as a video.

For example, in a system in which bits are provided on both sides of a recording track in response to signals with different frequencies, when the needle tip 2α shifts by K to either the left or right side of the recording track, the tracking information is determined by the magnitude of these two signals. Detected. Eye 1
(2) The needle control circuit 5 that has detected the tracking information outputs a signal for controlling the position of the needle 2 in accordance with this tracking information.

This signal is applied to the control coil 6. This allows the needle tip 2a to be accurately traced on the recording trunk. Note that the needle 2 is provided on the pickup arm 7.

In this way, needle 2 continues tracing and strands i12
When it reaches a predetermined position indicated by ', the detection switch 8 detects this. Detection number 4B outputted from this detection switch 8 is applied to the operating circuit 1°. Operation circuit 1
0, this detection signal causes the motor 16 to be activated via the motor body IElI enclosure 12 for a predetermined period of time.
make it work.

The rotation of this motor 15 is transmitted to the pulley 15α via a reduction gear 41114 provided as necessary.

As a result, the belt 16 that is hung between it and the other pulley 15b moves, and the pickup arm 7 that is interlocked with this belt 16 moves by a predetermined distance. Note that such an operation is repeated every time the needle 2 is moved to a predetermined position by tracing.

That is, the pickup arm 7 is moved intermittently.

FIG. 2 is a block diagram specifically showing the conventional pickup arm drive mechanism shown in FIG. 1.

In the figure, reference numeral 21 denotes a force punch lever, at the tip of which a needle tip 2g having the minute 11& described above is provided. Further, a magnet 25 is provided on the ridge.

This cantilever 21 has a support rod 22 made of an elastic body.
is supported by the pickup arm 7.

The magnet 25 at the rear of the cantilever 21 has a control coil 6a,
It is facing 6k. Therefore, this control coil 6 (
When a current corresponding to the tracking signal output from the needle control circuit 5 is supplied via the coil drive circuit 5α, the -stone 26 moves accordingly. Therefore, the needle tip 2α can accurately trace the recording track to f! The Rukoto.

In addition, in the case where tracking signals of different frequencies are recorded at the l1171 end of the recording track, the needle control circuit 5 separately detects the tracking signals of these two wave numbers, and the two detection outputs become louder. output a signal like this.

Further, the magnitude and direction of the current flowing through the control coils 6CL and 6bK are determined by the tracking information signal obtained from the signal read by the needle tip 2α and the signal detection circuit 3.

On the other hand, as described above, the output of the signal detection circuit 5 is applied to the signal processing circuit j84, and is supplied to the L-bar monitor 19, where scratch and other necessary processing has been performed, and is reproduced.

The switch 80 function shown in FIG. 1 is obtained in FIG. 2 by a low-pass filter 8α, a comparator 8b, and a reference voltage source 8C.

That is, when the tracing of the needle tip 2α progresses and the pickup arm 7 is stationary, the low-pass filter 8α and the comparator detect that the needle tip 2a has moved to a predetermined position near the limit where tracing can be performed. 8b.

This will be explained in detail below.

Control coil/L/6α by coil drive circuit 5α.

The signal voltage for tracking control applied to the controller 6b is passed through a low-pass filter 8α to the controller 8b.
to be applied. The comparator 8b compares the reference voltage with the reference voltage of the reference voltage source 8C and generates an output of 1 voltage when the voltage exceeds the reference voltage.

Note that if the polarity of the reference voltage of the reference voltage source 8C is changed according to the moving direction of the pink-up arm 7, the same control becomes possible even when moving in the opposite direction to the normal direction.

The output voltage of the comparator 8b is applied to the operating circuit 10 as explained in FIG.

The output of the operation circuit 10 is applied to the motor 15 via the motor drive circuit 12. As a result, the motor 1
5 is rotated in time -e, so that the pick-up arm 7 is aligned with the pulley IEl.

15b and the belt 16, it is moved by a certain distance.

The distance that the pickup arm 7 moves once is selected to be equal to or less than the movable range of the needle tip 2a that can be moved by the movement of the cantilever 21. Here, to give an example, the track width of a video disc is 1mJ equal to the track pinch.
．． In the case of 45riL, it can be selected to be about 150μ.

Figure 5 shows the needle control circuit 5 and coil drive circuit 5 in Figure 2.
FIG. 2 is a block diagram showing the vicinity of α in more detail.

In the figure, 51 and 52 are filters for separating tracking signals. That is, the signal detection circuit 3
(from S8, a filter 51,
52 are each tuned to the tracking signal. The two tracking signals output from these two filters 51 and 52 are sent to amplitude detection circuits 55 and 54, respectively.
and is detected here to detect the amplitude.

When these two detection voltages are applied to the differential amplifier 55,
The differential amplifier 55 detects the difference and uses it as a control signal.

Tracking g1 recorded superimposed on both sides of the recording track
If the frequency of the left tracking signal and the right tracking signal are in a constant relationship for any track, the output of the differential amplifier 55 may be directly supplied to the coil drive circuit 5a through the phase compensation circuit 5b.

However, in order to increase the recording density of a video disc, if there is no interval between tracks adjacent to each other, and if the tracking signal is shared between two tracks on both sides, then the frequency will change alternately.

Therefore, in the above-mentioned video disc, the switching signal indicating the switching point between the left and right frequencies of the tracking signal is placed in the portion corresponding to the blanking period of the normal image signal.
It is further recorded as a signal with a different frequency from the tracking signal.

Filter 56 is a circuit for separating this switching signal. The switching signal separated by this filter 56 is detected by a detection circuit 57 and controls a polarity inversion circuit 58. That is, the polarity of the output of the differential amplifier 55 is alternately reversed at the point where the left and right MllfIL numbers of the tracking ('!!) switch. By doing this, any trunk can receive an accurate tracking control signal. or can be obtained.

Further, in FIG. 3, 5CO is a reproduction mode selection circuit. A reproduction mode such as still image Fl or slow-mo mode reproduction is commanded to this circuit 5CO from the outside via a switch or the like through an input terminal 5C1.

Based on this command, for example, when the stationary mode is selected, the reproduction mode selection circuit 5CO sends the needle tip 2α (FIGS. 1 and 2) back to the original track when the video display rotates once. A signal is output that causes the drive to be forced back to . Coil drive circuit 5 receiving this signal
At α, this signal is superimposed on the control signal and the control coil 6
Apply to 6°-s.

It is convenient that the signal for forcibly driving the needle tip is generated during the vertical blanking period that is synchronized with the vertical synchronization signal obtained by the signal processing circuit 4. In this way, only the same track is repeatedly traced and the same signal I■] is repeatedly reproduced, so that a still signal can be reproduced.

Also, if you want to obtain other playback modes (for example, play every other track, reverse, etc.), you can also force the Necessary control is performed by superimposing a signal for moving the needle tip 2a on the control signal and sending it to the control coils 6a, d, b.

FIG. 4 is a circuit diagram showing a specific example of the operating circuit 10 and motor drive circuit 12 shown in FIGS. 1 and 2. FIG.

In the figure, 10α is an input terminal to which an output signal for detecting the position of the needle tip 2α outputted from a comparator sb<ta2 (see FIG. 2) is applied. 10A is a monostable multivibrator triggered by No. 1g applied to this input terminal 10cL.

As explained earlier, this fixed rate multivibrator 10b remains on for a predetermined time so that the distance the pickup arm 7 is moved is a predetermined distance. Becomes a high level.

100 and 10d are part of the operation switch, and 10
C is a forward rotation switch, and 1011t is a reverse rotation switch.

In the state of regeneration operation, either the stop rotation switch 1oc or the reverse rotation switch 10d is operated.

1 (1j is a switch Th1J11 circuit, which operates to transmit this information to the Nantes gate 10fK when the stop rotation switch 10C is operated, and transmits this information to the Nands gate 10fK when the reverse rotation switch 10d is operated. The switch control circuit 10f operates to transmit the signal to the gate 10&.This switch control circuit 10f can be constructed from a 7-way flip-flop.

When the forward rotation switch 10C is turned on, the Nantes gate 1
0! The output connected to i becomes high level. At this time, when a signal indicating that the position of the needle tip 2@ is at a predetermined position is applied to the input terminal 10aK, the output of the monostable multivibrator 10b remains at a high level for a certain period of time. As a result, the output of the monostable multivibrator 10b also passes through the OR gate 10e to the Nant gate 1.
07.

Therefore, the two inputs of the Nantes gate 10!0 are:
Becomes a high level. For this reason, the output of the Nant gate 10y remains at a low level for a certain period of time. Therefore, the transistor 12a turns on, and the inverting circuit 121
As a result, the transistor 12m is also turned on. Therefore, the motor 15 rotates so as to move the pickup arm 7 (FIGS. 1 and 2) in the forward direction only during the time that the monostable multi-by-break 'Oh is outputting the output voltage.

Furthermore, when the reverse switch 10m is operated and the output connected to the AND gate 10m becomes high level, when the output of the monostable multivibrator 10b becomes high level, the output to the AND gate 10 becomes high level. As a result, transistors 124 and 120 are turned on, as can be seen from the figure, and a current flows through motor 13 in the opposite direction to that previously described. That is, the motor 15 rotates to move the pickup arm 7 in the opposite direction.

In addition, fast forwarding (continuous movement) of the pickup arm 7 is as follows:
Switch S that is closed when fast forward operation is commanded
This is done by l. That is, when the switch S1 is closed, the power supply voltage is applied to the Nant gate 10! through the OR gate 110. and is applied to AND gate 10A.

Therefore, forward rotation switch 10C or reverse rotation switch 10m
If one of these is operated, fast forwarding is performed in accordance with the operation.

In the above explanation, a single inexpensive DC motor is used as the drive source to move the pickup arm at widely different speeds (i1il+ speed or low speed) and only a predetermined distance depending on each restraint mode. This was the case.

However, if the pickup arm is moved accurately and at a predetermined speed,
As is well known, it is preferable to use a pulse motor to move a predetermined distance. However, in order to move the regular JIK pickup arm using a pulse motor in any playback mode,
As is well known, a large pulse train is required. As a result, it has the disadvantage of being more expensive than when using a DC motor.

Furthermore, the pulse motor has the disadvantage that it requires a complicated acid path in order to change its driving frequency.

Therefore, as mentioned above, in the past, a single inexpensive DC motor was used instead of a pulse motor as a drive source to move the pickup arm at high or low speed and by a predetermined distance depending on each playback mode. method was adopted.

That is, in this system, when the pickup arm moves at high speed, such as in random access reproduction mode, the DC motor is continuously driven as described above. Furthermore, when the pickup arm moves at a low speed as in the normal reproduction mode, it is necessary to finely control the big amplifier arm, so the DC motor is driven in a pulsed manner.

Therefore, during low-speed playback, the pickup arm is
Moving and stopping operations will be repeated intermittently.

The jIs diagram is an example of the (b) path for measuring the rotation angle of the DC motor 13. FIG. 6 also shows the establishment results obtained by the circuit of FIG. In FIG. 6, the horizontal axis represents the pulse width, and the vertical axis represents the rotation angle (#). In addition, the song @ “*be” is set to the DC motor 15 (/, -cm
, Aly-ant, A, and g-cI@ are applied.

In FIG. 5, when a pulse with a pulse width i is applied to the input terminal 27, the transistor 25
It's only on for a certain amount of time. Therefore, the DC motor 13 rotates for that period of time.

However, as is clear from Figure 6, K.

Even if the DC motor 15 is driven with the same pulse width, the rotation angle (-) will vary greatly depending on the load applied to the DC motor 1S. Therefore, if a DC motor having such characteristics is used as a drive source for a pickup arm of a video disc playback device, the following problems may occur.

In other words, for example, the load on the DC motor may change due to play in the pickup arm support system, etc. In such cases, even if the DC motor is driven with a constant pulse width, the pickup arm will The phenomenon of not moving or, conversely, of moving too much may occur.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to minimize changes in the rotation angle even if the load on the free-current motor changes when the direct-current motor is driven with pulses having a constant pulse width. An object of the present invention is to provide a pulse drive device for a DC motor that can be made small.

In order to achieve the above object, the present invention uses the following means such as a DC motor to perform pulse driving.

(1) Between the DC motor's spoon and start point,
By applying a sufficiently high voltage to the DC motor,
Drive.

(2) After the start-up period, the current motor is driven by an electronic governor circuit that controls the number of revolutions (@turn angle) to approximately a predetermined number regardless of the load applied to the DC motor.

C) When stopping the driving of the DC motor, the driving is stopped by a stopping means that shorts the terminals of the DC motor so that the DC motor can be stopped instantaneously.

Hereinafter, the present invention will be explained using the drawings.

@7 Figure is a circuit diagram showing an embodiment of a pulse drive device for a DC motor according to the present invention. In the same figure, the part 26 surrounded by a broken line is an electronic governor circuit, 28 and 29 are input terminals, and 5
0.51.52 is a transistor. Note that 13 indicates a DC motor as in FIGS. 4 and 5.

When a drive pulse that is at a high level for the tw waiting time is input from the input terminal 28, the signal 73 is input from the other input terminal 29.
When a pulse that goes to the p- level for a time (start-up start period, t+ (1'w)) is input, the transistor 31 is turned on and the transistor 52 is turned off.As a result, the start-up start period at the beginning of the drive pulse/ In this case, a power supply voltage of +B is directly applied to the DC motor 1s.

Therefore, at the start-up of the DC motor 1s, the starting torque can be made sufficiently large. That is, even if the load on the free-flow motor 16 changes, the DC motor 13 can be reliably started without being affected by the change.

Furthermore, the 1&amp; current rise of a DC motor is limited by its inductance component. However, if the inductance component is constant, the rate of increase in current can also be increased by increasing the voltage applied to the DC motor. In this embodiment, as described above, since the power supply voltage of 10 B is directly applied to the motor 15 when starting the DC motor 13, a high current increase rate can be achieved when starting the DC motor 13. As a result, the DC motor 15 can be started quickly. Note that the electronic governor circuit 26 is reliably activated during the activation start period t1.

Next, after the startup start period /I has elapsed, the input terminal 29
Since the pulse input from changes to high level,
Transistor 31 is turned off. Therefore, although the power supply voltage of 10 B is not directly applied to the DC motor 15, the transistors 50 and 32 are kept in the OFF state, so that the DC motor 13 is not directly applied to the electronic governor circuit 26.
It will be driven by. As a result, the DC motor 15 is controlled so that the rotational speed does not change even if the load changes.

After the tw waiting time has elapsed, when the drive pulse input from the input terminal 28 becomes low level, the transistors 50 and 32 change from off to on. When the transistor 50 turns on, the electronic governor circuit 26
operation is stopped. Further, when the transistor 52 is turned on, the terminals of the DC motor 15 are short-circuited. That is, the rotation of the DC motor 13 is stopped instantaneously at the same time as the tw time elapses.

As is clear from what has been stated above, the DC motor 1
The voltage applied to i5 is the power supply voltage VB of 10B during the start-up period 11, after which it becomes VS controlled by the electronic governor circuit 26, and further after the tw time corresponding to the drive pulse width has passed. , at one time becomes UV. Therefore, the voltage applied to the DC motor 15 becomes K, a step-wave voltage V, as shown in 8-.

Figure 9 shows the measurement results obtained with the circuit of Figure 7. In the figure, the horizontal axis is the pulse width, and the vertical axis is the rotation angle (#).
represents. In addition, curves α, b, and c are similar to Figure 6,
U y-cm and 4 g- for the DC motor 13, respectively.
The characteristics when a load of crn, A, y-cm is applied is shown.

As is clear from the comparison between the "f off" measurement results shown in FIG. 9 and the measurement results shown in FIG. 6 described above, when the DC motor 15 is driven using the circuit shown in FIG. Good 1: Changes in rotation angle (-) are extremely small even when load fluctuates.
I was able to obtain kj results.

Next, a case where the pulse drive device for a scoop motor according to the present invention is applied to drive a pickup arm of a video disc playback device will be described with reference to FIG. 10. In the figure, 40 is a forward rotation input terminal, 41 is a reverse rotation input terminal, and 4
2 is a stop pulse input terminal, 43 is an inversion circuit, 44.45
is an OR circuit. In addition, the same parts and the same parts as No. 7m are indicated by the same reference numerals.

A high-level signal is input to the stop pulse input terminal 42 except when a stop pulse, which will be described later, is input. In such a state, when a pulse of a predetermined width is input from the normal rotation input terminal 40, the transistor 12d is turned on, and the step wave voltage VM explained in FIG.
is applied to the DC motor 13 via the transistor 12K.

Furthermore, when a pulse of a predetermined width is input from the reverse input terminal 41, the transistor 127 is turned on, and the step-wave voltage V, also explained in FIG. 7, is applied to the DC motor 1 through the transistor 12C. be done.

Here, the short-circuiting of the terminals of the DC motor 15 at the same time as the elapse of the tW time will be explained using FIG. 11. When the tsm time has elapsed, the drive pulse input from the forward or reverse rotation input terminal 40 or 41 becomes low level. At this time, from the stop pulse input terminal 42,
As shown in Figure 1, the stop pulse S remains low for a certain period of time.
T is input.

As is clear from FIG. 10, this stop pulse ST is as follows.
The signal is simultaneously supplied to transistors 12b and 124 through inverting circuit 43 and OR circuits 44 and 45. Therefore, the transistors 12 and 12m have fw
It remains off for a certain period of time even after the time has elapsed. For this reason, the terminals of the DC motor 15 are short-circuited.

Therefore, the DC motor 13 rotates by a predetermined rotation angle, regardless of load fluctuations. As a result, the pickup arm 7 (see Figures 1-2), which is interlocked with the DC motor 1S, can also stably move by a predetermined width.

As is clear from the above explanation, in the pulse drive device for a DC motor of the present invention, even if the load applied to the DC motor changes, there is almost no change in its rotation angle, and stable driving is possible. .

Therefore, the pulse drive device for a DC motor of the present invention is
If applied to the pickup arm drive mechanism of a video disc playback device, the movement of the pickup arm during pulse drive will be stabilized, so that the pickup arm can be moved without shifting.

[Brief explanation of drawings]

Diagram 1 shows the conventional pickup arm drive mechanism.
Figure s ls2 is a block diagram showing an example of the configuration of Figure 1, and Figure swA is a block diagram showing the needle control circuit 5 and coil drive circuit 5G shown in Figure 2 in detail. Figure 4 shows a concrete example of the sub-operation path 10 and the cage drive circuit 12 shown in Figures 1 and 2, and Figure 5 shows a direct current circuit. Encircle-1 showing an example of a circuit for measuring the pulse radiation angle 4I
FIG. 6 shows the constant 11! obtained by the circuit of swA! I.J.
The first figure is a circuit diagram showing one embodiment of Honto's DC motor pulse drive device, and the first figure is an example of the relationship between the pulse width and the step wave voltage FM applied to the DC motor. FIG. 9 is an explanatory diagram showing the pulse width-[1 rotation angle 4I property of the DC motor obtained according to an embodiment of the present invention, 1s10
The figure is a line diagram showing an application example of the pulse drive device for a DC motor of the present invention, and FIG. 11 is a waveform diagram showing an example of waveforms input from each input terminal of the 10th wJ. 1s...DC circuit 26...electronic gap circuit 28.2? ...Input terminal RO-32--transistor/? 1 country/θ 2nd opening 4[Xl 5th opening 71, +? [! ] Pulse smoothness

Claims (1)

[Claims] (1) A pulse drive device for a DC motor that drives a DC motor with pulses having a constant pulse width, comprising: a starting means for applying a sufficiently high voltage to the DC motor during a starting period of the DC motor; an electronic governor circuit that controls the rotational speed (rotation angle) of the DC motor to a predetermined number regardless of the load applied to the DC motor after the start-up period; What is claimed is: 1. A pulse drive device for a direct current motor, characterized by comprising a stop means for short-circuiting terminals.